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    <meta charset="UTF-8">
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    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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<body>
    <script>
    // async    只要在函数前面加上async关键字，函数的返回值就会变成promise
    async function go(){
        return 1
    }
    go().then(res=>{
        console.log(res);
    })
    var show =async ctx => {
        return 1
    }
    console.log("@@",show());
    </script>
</body>
</html>